rev vs rate

rev and rate both are nouns.

Word	Noun	Adjective	Verb	Adverb
rev	Yes	No	Yes	No
rate	Yes	No	Yes	No

As nouns, rate is a hypernym of rev; that is, rate is a word with a broader meaning than rev:

rev (noun)	rate (noun)
rate of revolution of a motor	the relative speed of progress or change
	amount of a charge or payment relative to some basis
	a quantity or amount or measure considered as a proportion of another quantity or amount or measure
	a magnitude or frequency relative to a time unit

rev (verb)	rate (verb)
increase the number of rotations per minute	assign a rank or rating to
	estimate the value of
	be worthy of or have a certain rating